Heat exchangers, of which there are numerous types, are employed for heating or cooling a liquid product. With the aid of, for example, steam or water at different temperatures, it is possible to impart to the product a desired temperature. Heat exchangers come into use within many various processing industries and also commonly occur in food processing plants such as dairies or juice factories.
One well-known type of heat exchanger is the so-called tube heat exchanger. This consists of one or more heat exchanger elements which are interconnected to form a flow system. The heat exchanger elements comprise one or more heat transfer tubes surrounded by an outer jacket or casing tube. The heat transfer tubes are interconnected to form product inserts which in turn are interconnected by means of product pipe bends intended to circulate the product which is to be heated or cooled, depending on what process the heat exchanger is employed for. The heat transfer tubes are enclosed in a jacket or casing tube which also encloses the thermal transfer medium. Mutually adjacent casing tubes are interconnected to circulate the thermal transfer medium. The thermal transfer medium may consist of water at different temperatures, steam or other types of liquids or gases. One such heat exchanger is described in Swedish Patent Specification SE-501 908.
In order to increase the degree of efficiency of the heat exchanger, it is occasionally desirable to employ one or more heat exchanger elements as regenerative sections, i.e. the product which has been heated in the heat exchanger is caused to heat up the incoming, cold product. The incoming, cold product then consequently contributes in cooling the ready-treated, heated product. In order to employ an above-described tube heat exchanger regeneratively, product must be located in both the heat transfer tubes and in the casing tube which surrounds the heat transfer tubes. Such a process may considerably cheapen a complete tube heat exchanger and also reduce the energy consumption for the process which takes place in the tube heat exchanger.
The heat transfer tubes, enclosed in their casing tube, normally are of a length of approximately 6 m. In order that the tubes are not exposed to unnecessary stresses from vibrations or sagging, they must be supported at one or commonly more points along their length. If the heat transfer tubes sag or vibrate so that they touch one another, thermal transfer surface area is lost and the tube heat exchanger will not be as efficient as may be expected. Shorter tube lengths must also most generally be supported. The support points which are employed may be of various designs and forms and are most generally designated—employing a common name—so-called baffles. When only water or steam is employed as the thermal transfer medium, few or no requirements are placed on the form and design of these baffles, apart from the fact that they are to separate the heat transfer tubes from one another and prevent the heat transfer tubes from coming into contact with the inner wall of the casing tube.
When it is desired to employ a heat exchanger element regeneratively, utterly different requirements are immediately placed on a hygienic design with full washing capability. In those cases when the product contains fibres or small particles, such as fruit juices, these requirements are even more stringent. Attempts have been made to design the baffles so as to have as rounded-off surfaces as possible in order to avoid the risk that the fibres or particles of the product become accumulated. However, in practice it has proved difficult to obtain such a design of the baffles. Problems have also been encountered in causing the baffles to surround the heat transfer tubes without pockets being formed. All baffles entail more or less that something is located at right angles to the direction of flow of the product and, as a result, there is also always a risk of the accumulation of particles or fibres which may jeopardise the cleaning operation and ultimately give rise to production disruptions.